Thermal displacement errors are becoming more and more important in the precision engineering field where the specifications are ever increasing. This paper proposes a novel technique to compensate in-plane thermal displacement errors in a thin plate under a moving disturbance heat load. The displacement error is evaluated at the point of the moving heat load. The technique utilizes Thermal Modal Analysis (TMA) as a means to analyze the transient temperature distribution in the plate and estimate the thermal displacement field resulting from that temperature field. The temperature field is controlled by applying additional heat loads to the plate to control and eliminate some of the modes in the temperature domain which have the largest influence to the thermal displacement error. The theory of thermal modal analysis and the developed technique of controlling modes in the temperature domain are explained. The experimental setup and results are shown to validate the control of the thermal modes. (C) 2015 Elsevier Inc. All rights reserved.

Thermal errors are important sources of positioning errors in precision machines and are more and more becoming determining factors to meet increasing specifications. In this paper, thermal modal analysis is used to study and reduce the transient thermal displacement errors in precision machines. The temperature decomposition and the thermal displacement field decomposition by thermal modal analysis are derived. The reduction of transient thermal errors by adding additional heat loads is analyzed and the results of two different methods are compared.

A new contact-less transport system for thin and fragile products like silicon wafers is introduced. The product is carried on a thin film of air separating the product from the system, and is transported using the relative velocity of the pressurized and moving air film parallel and adjacent to the system surface. This innovative concept can produce both the high stiffness and acceleration required for high precision positioning and efficient product transport. In this paper the basic design principles of this system are presented. Experimental verification is demonstrated on a 6-dof planar air actuated high precision positioning stage.

In precision machines well designed vibration isolation systems isolate the accurate machine components from the surroundings, while at the same time suppressing reaction forces originating in the positioning systems of the machine itself. The isolation function requires an actuator with a low stiffness. For a machine with high accelerations, these reaction forces can typically go up to 300 N. The suppression of reaction forces demands an actuator capable of generating equally large reaction forces. Next to this the actuators dissipation should be minimised to limit thermal load on accurate machine components. A new linear actuator is developed capable of meeting all three requirements.

INTRODUCTION One of the future challenges in the design of semi-conductor manufacturing equipment is the introduction of 450 mm wafers. In these machines the wafer is generally held and positioned on a wafer chuck. The position of the wafer chuck is controlled in an active position feedback loop, where it is assumed the wafer chuck behaves as a rigid body. As the wafer area increases so does the chuck’s surface. To limit internal flexibility and keep internal eigen-frequencies at high levels, the chuck’s thickness has to be increased as well. This leads to a significantly increased mass. In combination with the continuous demand for higher throughput this results in enormous acceleration forces. High acceleration forces risk perturbing accurate machine components, and lead to large power consumption and heat dissipation.

High control performance is essential in many precision positioning applications, such as control of the vertical sample position in a atomic-force microscope (AFM). This paper investigates the impact of load flexibility on piezoelectrically actuated positioning systems in terms of control performance. The modeling method used combines modal analysis with simple transfer function manipulations, and shows, how the load dynamics may influence the control performance. The analysis is experimentally verified on a commercial AFM system.

In this paper a new contactless transport system for thin, flat products, such as glass substrates and silicon wafers, is introduced. The transport function is realized using viscous traction on the product surface. After an explanation of the operating principles, a mathematical model is presented. Preliminary computations indicate that the generated acceleration is approximately 2.5 m/s2 for a glass substrate with a surface area of 2 m2 and a thickness of 0.7 mm. Furthermore, the vertical bearing stiffness for the considered actuator geometry of the system is 4.2·106 N/m, depending on the properties of the inflow and outflow points of the actuator cells.

In this paper a new two-degree of freedom actuator for suspension and propulsion is presented. The actuator has the potential to become a building block in a high precision six degree of freedom motion system. The actuator is called the IU-module, the topology stems from the I-shaped rotor and the U-shaped stator. The working principle behind the suspension of an IUmodule is the reluctance force. The propulsion works on the moving iron principle, presented by Molenaar [1]. Improved modeling using a network of variable reluctances and finite element models give a good indication about the static performance of the IU-module. A demonstrator has been constructed to evaluate the dynamic performance of the IU-module. The achieved resolution for this demonstrator is 1 μm in suspension direction and 0.3 μm in the propulsion direction. The limiting factors are the used position sensors.